I INTRODUCTION  
Microcomputer, desktop- or notebook-size computing device that uses a microprocessor as its central processing unit, or CPU (see Computer). Microcomputers are also called personal computers (PCs), home computers, small-business computers, and micros. The smallest, most compact are called laptops. When they first appeared, they were considered single-user devices, and they were capable of handling only four, eight, or 16 bits of information at one time. More recently the distinction between microcomputers and large, mainframe computers (as well as the smaller mainframe-type systems called minicomputers) has become blurred, as newer microcomputer models have increased the speed and data-handling capabilities of their CPUs into the 32-bit, multiuser range.

Microcomputers are designed for use in homes, schools, and office settings. Within the home, they can serve both as a tool for home management (balancing the family checkbook, structuring the family budget, indexing recipes) and as a recreational device (playing computer games, cataloging records and books). Schoolchildren can use microcomputers for doing their homework, and in fact many public schools now employ the devices for programmed learning and computer-literacy courses. Small businesses may purchase microcomputers for word processing, bookkeeping, and the storage and handling of mailing lists.

II ORIGINS  
Microcomputers were made possible by two technical innovations in the field of microelectronics: the integrated circuit, or IC, which was developed in 1959; and the microprocessor, which first appeared in 1971. The IC permitted the miniaturization of computer-memory circuits, and the microprocessor reduced the size of a computer's CPU to the size of a single silicon chip.

Because a CPU calculates, performs logical operations, contains operating instructions, and manages data flows, the potential existed for developing a separate system that could function as a complete microcomputer. The first such desktop-size system specifically designed for personal use appeared in 1974; it was offered by Micro Instrumentation Telemetry Systems (MITS). The owners of the system were then encouraged by the editor of a popular technology magazine to create and sell a mail-order computer kit through the magazine. The computer, which was called Altair, retailed for slightly less than $400.

The demand for the microcomputer kit was immediate, unexpected, and totally overwhelming. Scores of small entrepreneurial companies responded to this demand by producing computers for the new market. The first major electronics firm to manufacture and sell personal computers, Tandy Corporation (Radio Shack), introduced its model in 1977. It quickly dominated the field, because of the combination of two attractive features: a keyboard and a cathode-ray display terminal (CRT). It was also popular because it could be programmed and the user was able to store information by means of cassette tape.

Soon after Tandy's new model was introduced, two engineer-programmers—Stephen Wozniak and Steven Jobs—started a new computer manufacturing company named Apple Computers. Some of the new features they introduced into their own microcomputers were expanded memory, inexpensive disk-drive programs and data storage, and color graphics. Apple Computers went on to become the fastest-growing company in U.S. business history. Its rapid growth inspired a large number of similar microcomputer manufacturers to enter the field. Before the end of the decade, the market for personal computers had become clearly defined.

In 1981, IBM introduced its own microcomputer model, the IBM PC. Although it did not make use of the most recent computer technology, the PC was a milestone in this burgeoning field. It proved that the microcomputer industry was more than a current fad, and that the microcomputer was in fact a necessary tool for the business community. The PC's use of a 16-bit microprocessor initiated the development of faster and more powerful micros, and its use of an operating system that was available to all other computer makers led to a de facto standardization of the industry.

III LATER DEVELOPMENTS  
In the mid-1980s, a number of other developments were especially important for the growth of microcomputers. One of these was the introduction of a powerful 32-bit computer capable of running advanced multi-user operating systems at high speeds. This has dulled the distinction between microcomputers and minicomputers, placing enough computing power on an office desktop to serve all small businesses and most medium-size businesses.

Another innovation was the introduction of simpler, "user-friendly" methods for controlling the operations of microcomputers. By substituting a graphical user interface (GUI) for the conventional operating system, computers such as the Apple Macintosh allow the user to select icons—graphic symbols of computer functions—from a display screen instead of requiring typed commands. New voice-controlled systems are now available, and users may eventually be able to use the words and syntax of spoken language to operate their microcomputers.

Contributed By:
Gary Masters
Courtesy www.rediff.com